1. Field
The present invention relates to an apparatus for measuring blood sugar concentration, and more particularly, to a noninvasive biosignal measurement apparatus and method which can accurately measure blood sugar concentration by correcting a hemoglobin (Hb) concentration measurement using a tissue modulation technique.
2. Description of the Related Art
As improved lifestyles have enriched our lives, peoples' concerns about their health also have increased. Therefore, research about home medical appliances which enable a user to readily test the user's health status at all times is being conducted, and new products are also being developed. When the user is in a normal health status, body fluids organically circulate and are adjusted, and thus a constant amount of body fluids are maintained. The body fluids include components, such as blood, urine, interstitial fluids, sweat, saliva, and the like. In particular, each component concentration in the body fluids, such as blood, urine, and the like, becomes a very important parameter to inform the user of the health status. Also, it is necessary to measure the concentration of glucose, hemoglobin (Hb), bilirubin, cholesterol, albumin, creatinine, protein, or urea, in the blood. However, when a living body is infected with any disease, a composition or amount of various components in the body fluids may change, so that the user may encounter an emergency situation. For example, a healthy user maintains a blood sugar concentration at about 80 mg/dl (mg per 100 cm3) before meals, and about 120 mg/dl after meals. To maintain the blood sugar concentration at a constant level, the pancreas produces an appropriate amount of insulin before and after meals, that causes the produced insulin to be absorbed in tissues of the liver and the skeletal muscle. However, when the pancreas does not produce sufficient insulin to maintain normal blood sugar concentration due to diseases or other causes, huge amounts of glucoses may exist in the blood, which may cause a cardiac disorder, arteriosclerosis, hypertension, cataract, cyanosis retinae, neural damage, loss of hearing, diminution in acuity of vision, and the like. Also, in a worst case, the user may die. Accordingly, it is very important to measure the change in the body fluids' components before an extreme incident occurs.
A method of measuring the component concentration of body fluids includes an invasive method of directly drawing a portion of a target component from the body, and measuring the concentration of the target component, and a noninvasive method of measuring the concentration of the target component without directly drawing the target component from the body. In this instance, due to some problems caused by the invasive method, a noninvasive technology capable of readily diagnosing a component in blood is being developed. In a conventional method of measuring the blood sugar concentration, a user draws blood, reacts the drawn blood with a diagnostic reagent, and diagnoses the blood using a clinical analyzer or a color change of a test strip reacted to the diagnostic reagent. However, the conventional method may inflict pain upon a diabetic patient since the diabetic has to draw blood every day. Also, the diabetic patient may become infected with another disease due to repeated operations of drawing blood. Also, the conventional method has disadvantages in that an emergency situation may not be readily handled since constant monitoring is impossible. Also, the diabetic patient may feel a huge economical burden since a great deal of strips and diagnostic reagents are used, and thus also results in environmental pollution.
Accordingly, there is a need for a technology which can measure blood sugar concentration without drawing blood and without a strip and a diagnostic agent so that a diabetic patient may control his blood sugar concentration, or a healthy user may examine a medical test.